JPH0497519A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To curtail growth period and improve throughput by forming a base layer of thin plysilicon thin film on a silicon substrate in the initial growth stage under the condition of low temperature selective polysilicon growth and then allow the growth of polysilicon film under the condition of a high temperature selective epitaxial growth. CONSTITUTION:After forming a silicon oxide film 9 on a single crystalline silicon substrate 7, a contact hole 8 is formed thereon. Next, a thin polysilicon film 10 is selectively grown on a substrate 7, growth is once stopped, and temperature is raised. Thereafter, polysilicon is selectively grown only on the film 10 and a thick polysilicon film 10 is grown. Namely, a base layer of thin polysilicon film is formed on the silicon substrate under the condition of low temperature selective polysilicon growth and then a polysilicon film is grown under the condition of high temperature selective epitaxial growth. Thereby, a growth time can be curtailed and throughput can also be improved remarkably.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a selective polysilicon growth method.

[Conventional technology]

Selective epitaxial growth is a hole-filling technique for selectively growing silicon in the openings of a silicon substrate covered with an oxide film (Japanese Patent Laid-Open No. 57-37829).

As shown in FIG. 4(a), a single crystal silicon substrate 7 covered with an insulating film 12 having a contact hole 8 is covered with a silicon epitaxial layer 13 as shown in FIG. 4(b).
grow.

At this time, without depositing silicon on the surrounding insulating film 12, an epitaxial layer 13 made of single crystal silicon having the same crystal orientation as the underlying single crystal silicon 7 is formed only on the single crystal silicon 7 so as to fill the hole. , is grown to a thickness approximately equal to that of the insulating film 12.

If an attempt is made to form a wiring layer in the state shown in FIG. 4(a), thin portions will occur in the electrode wiring layer 14 as shown in FIG. However, if a wiring layer is formed in the state shown in FIG. 4(b) after selective epitaxial growth, a flat wiring layer 14 can be formed as shown in FIG. 5(b).

Selective epitaxial growth is performed using dichlorosilane (S1H2C
At the same time, the silicon epitaxial layer 13 is deposited on the single-crystal silicon substrate 7 by thermally decomposing or reducing a silane-based gas such as ρ2) with hydrogen (H2), and at the same time, the polysilicon deposited on the insulating film 12 is heated with hydrogen chloride (H2). This is achieved by etching with HCJ).

By selecting the flow rate of hydrogen chloride, selective epitaxial growth is achieved in which the silicon epitaxial layer 13 grows only in the contact hole 8 without depositing polysilicon on the insulating film 12.

To give an example of growth conditions, a silane-based gas such as dichlorosilane (SiHzCfflz), hydrogen (H2) and hydrogen chloride (HCj) are used so that dichlorosilane:hydrogen chloride=2=1 at a growth temperature of 850°C. Let the gas flow.

Another selective polysilicon growth is to grow a polysilicon film 10 in the contact hole 8 as shown in FIG. 4(C).

When forming the emitter of a bipolar transistor, planarization technology using hole filling is particularly important.

If As is ion-implanted directly into a single-crystal silicon substrate, a shallow emitter junction cannot be formed, so it is impossible to obtain a high t-current amplification factor or high-frequency characteristics.

Therefore, in the case of an NPN transistor, after forming a base layer 15 as shown in FIG. 6(a) and forming a silicon oxide film 9 having a contact hole 8, as shown in FIG. 6(b), A polysilicon film 10 with a thickness of 200 nm is deposited in the contact hole 8 .

Thereafter, as shown in FIGS. 6C and 6D, N-type impurities such as As are ion-implanted and diffused by annealing to form a shallow N-type emitter layer 16. The polysilicon film 10 usually also serves as a lead-out for emitter wiring.

Conventionally, a regular polysilicon film 10 was simply grown on a single-crystal silicon substrate 7, but with the miniaturization of integrated circuit patterns, the size of contact holes has reached the submicron order and the aspect ratio has increased. , planarization technology has become important, and selective polysilicon growth has become important.

Furthermore, there is a method in which silicon is selectively grown in a contact hole in which a metal silicide layer is selectively buried (Japanese Patent Laid-Open No. 58-34916).

In this case, a metal silicide layer is required to provide selectivity, which increases the number of steps, and it cannot be used for emitter formation.

The growth of selective polysilicon film 10 directly filling contact hole 8 on single crystal silicon substrate 7 as shown in FIG. 4(C) has not been put to practical use.

Lowering the growth temperature of selective epitaxial growth to 750°C,
By changing the gas conditions to dichlorosilane:hydrogen chloride=8:1, a selective polysilicon film 10 is deposited in the contact hole 8 instead of the epitaxial film 13, as shown in FIG. 4(c). Growth is achieved.

[Problem to be solved by the invention]

In the conventional polysilicon growth method, polysilicon is grown only on silicon by etching with hydrogen chloride. Furthermore, if the growth temperature is raised, epitaxial growth occurs and polycrystalization does not occur, so the growth temperature cannot be raised.

Therefore, there is a drawback that the growth rate is about one order of magnitude slower than that of selective epitaxial growth.

[Means to solve the problem]

In the manufacturing method of a semiconductor device of the present invention, in the early stage of growth, a polysilicon thin film is formed on a silicon substrate under low-temperature selective polysilicon growth conditions, and then a polysilicon thin film is formed on a silicon substrate under high-temperature selective epitaxial growth conditions. It grows a film.

〔Example〕

First, a vapor phase growth apparatus for polysilicon films used in the present invention will be explained with reference to FIG.

A growth substrate 4 is fixed on a rotating substrate support 5 in a chamber 3 made of quartz glass.

The growth substrate 4 is provided with infrared lamps 2 around the chamber 3.
is heated to a predetermined temperature.

A reactive gas inlet 1 is provided at the top of the chamber 3, and a silane gas such as dichlorosilane, hydrogen, and hydrogen chloride for growing a silicon thin film are blown onto the growth substrate 4.

Gas not involved in the growth is exhausted through the gas outlet 6 by a vacuum pump.

Next, regarding the first embodiment of the present invention, FIGS.
This will be explained with reference to (c).

First, as shown in FIG. 2(a), a silicon oxide film 9 with a thickness of 500 nm is formed on a single-crystal silicon substrate 7, and a contact hole 8 with a planar size of submicron to several microns is further formed.

Next, as shown in Fig. 2(b), dichlorosilane was poured into the chamber at a pressure of 30 Torr and a temperature of 750°C.
A thin polysilicon film 10 with a thickness of 30 nm was selectively grown on the single crystal silicon substrate 7 by flowing 0QSCCm and hydrogen chloride for 50 seconds so that the ratio of dichlorosilane and hydrogen chloride was 8=1. .

Next, as shown in Figure 2(c), after stopping the growth and raising the temperature to 850°C, 300 se of dichlorosilane was added so that the ratio of dichlorosilane and hydrogen chloride was 2=1.
cm, and hydrogen chloride was flowed at 150 sec for 10 minutes. Then, polysilicon selectively grew only on the polysilicon film 10, and a thick polysilicon film 10 with a thickness of 200 nm was grown.

The selected polycrystalline silicon with a thickness of 200 nm is intended for forming the emitter of a bipolar transistor.

The growth rate under the growth condition of 850°C is 17 nm/mi.
This is approximately 10 times the growth rate (1.5 nm,/min) at 750°C.

If a silicon thin film were suddenly grown on the single-crystal silicon substrate 7 under conditions of 850° C., selective epitaxial growth would occur, making it impossible to grow polysilicon at such a fast rate.

In the present invention, after first growing polysilicon with various crystal orientations as a base, it was possible to continue selective growth of polysilicon without epitaxialization even at high temperatures.

In this example, considering the time to raise the temperature to 850°C, it took a total of 50 minutes to grow selective polysilicon with a thickness of 200 nm, and the actual growth time with gas flowing was 30 minutes. Ta.

In the conventional method, it took 100 minutes for one growth, so according to the present invention, the growth rate is effectively doubled.

Next, as a second embodiment of the present invention, filling of contact holes will be described with reference to FIGS. 3(a) to 3(c). The device used here is the same as in Example 1.

First, as shown in FIG. 3(a), a contact hole 8 is formed on a silicon substrate 7, and a thickness of 500 nm is formed to serve as an insulating film.
m of P S G (phospho-silicate
A glass) film 11 is formed.

Next, as shown in FIGS. 3(b) and 3(c), a polysilicon film 10 having the same thickness as PSG IIll is selectively grown in the contact hole 8.

The growth conditions are the same as in the first embodiment, and first, as shown in FIG. 3(b), a polysilicon film 10 with a thickness of 30 nm as a base is grown at 750° C. for 20 minutes.

Next, as shown in FIG. 3(c), once the growth is stopped and the temperature is raised to 850° C., the polysilicon film 10 is coated with dichlorosilane for 300 seconds and hydrogen chloride for 150 seconds.
The contact hole 8 made in the PSG film 11 was filled with a polysilicon film IO.

As a result, the time it took to grow a 500 nm thick polysilicon film IO in the contact hole 8 was 70 minutes, including the time to raise the temperature from 750°C to 800°C. With the conventional growth method of only 750°C, the growth rate is slow at 1.5 nm/min, so it takes 300 minutes to grow 500 nm, but this means that the growth time has been significantly shortened. .

In the case of filling such a contact hole, a larger growth film thickness is required than in the case of emitter formation, so that the effect is even greater.

〔Effect of the invention〕

At the early stage of growth, a polysilicon FF film is formed on the silicon substrate under low-temperature selective polysilicon growth conditions, and then the polysilicon film is subsequently grown under high-temperature selective epitaxial growth conditions to shorten the growth time. This has the effect of significantly increasing throughput.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a vapor phase growth apparatus for selective polysilicon used in the present invention, FIGS. 2(a) to (c) are cross-sectional views showing the first embodiment of the present invention in order of process, Figures (a) to (c) are cross-sectional views showing the second embodiment of the present invention in order of process, and Figure 4 (
a) to (c) are cross-sectional views showing selective growth by conventional technology;
5(a) and 5(b) are cross-sectional views showing electrode wiring, and FIG.
3A to 4D are cross-sectional views illustrating the formation of an emitter of an NPN transistor in the order of steps; 1... Reaction gas inlet, 2... Infrared lamp, 3...
...Chamber, 4...Growth substrate, 5...Substrate support, 6...Gas exhaust port, 7...Single crystal silicon substrate, 8...Contact hole, 9...Silicon oxide film,
1o...Polysilicon film, 11...PSGWi, 1
2... Insulating film, 13... Silicon epitaxial layer, 14... Electrode wiring layer, 15... Base layer, 16...
...Emitsuta layer.

Claims (1)

[Claims] A single crystal silicon substrate covered with a silicon oxide film having an opening is selectively grown thinly in the opening at a first growth temperature, and then a second growth is performed at a temperature higher than the first growth temperature. A method of manufacturing a semiconductor device, comprising selectively growing polysilicon thickly in the opening at a temperature.